We begin with the standard form of the Kerr metric [1]} in the Boyer-Lindquist coordinates [2]}:
\(ds^2=-F^2_t dt^2-2\omega F_t \,dt d\varphi +F^2_r dr^2+\rho ^2(r,\theta ) d\theta ^2+F^2_\varphi d\varphi ^2,\) 
